Catalyst- and solvent-free reaction of pyridine-d5 with secondary phosphine oxides and sulfides and phosphinic acid esters in the presence of benzoylphenylacetylene (50-55 or 70-75 °C, 7-35 h) gives 4-phosphorylated pyridines-d4 and -d3 (the latter having hydrogen at position 2) in 43-73% total yield along with differently deuterated chalcones, the reduced benzoylphenylacetylene. The scrutinized analysis of deuterium distribution in the above substitution products with emphasis on protium insertion in the pyridine ring reveals that the substitution studied involves the isomerization of the primary 1,3(4)-dipole intermediate to carbene localized at the position 2. Quantum chemical calculations (B3LYP/6-311++G**) indicate that diphenylphosphine oxide or trace water likely mediates the carbene generation stage.

Terminal alkynes undergo oxidative cross-coupling with secondary phosphine selenides in the presence of 3 mol% Pd(OAc)(2) and 1 equivalent of Et3N in CCl4 at room temperature to provide alkynylphosphine selenides in up to 65% yields. This new C-sp-P-forming reaction was proved to proceed via intermediate chlorophosphine selenides.

The chemodivergent base-mediated (KOH, 90 degrees C, 10 min) reaction of aromatic (heteroaromatic) nitriles with acetylene gas to yield 2,4-di(het)aryl pyrimidines (self-organization of two molecules of nitrile and one molecule of acetylene) and 2-(het)aryl pyridines (self-organization of one molecule of nitrile and two molecules of acetylene) has been developed. The chemoselectivity of these cascade processes was found to be unusually strongly controlled by the composition of the solvent. The effect of sulfolane was especially pronounced: When added to DMSO, it enabled the synthesis of pyrimidines exclusively in yields of up to 71%, whereas in DMSO with a small amount of MeOH, only pyridines were formed in yields of up to 36%. Given the fact that acetylene gas is an industrially available feedstock, the synthesis of 2,4-di(het)aryl pyrimidines developed here is becoming technologically feasible.

1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) cyclizes with a,b-ynones under catalyst-free conditions (MeCN, 3 h) to give a mixture of isolable diverse fused heterocycles including [3 + 3]- and [4 + 2]-cycloadducts as well as DBU ring expansion products, 14-and 15-membered heterocyclic systems incorporating the pyridinone moiety, in 48-58% total yield. Some of the synthesized cycloadducts exhibit blue-green fluorescence with large Stokes shift.

An efficient approach to access diversely substituted pyridines via a three-component reaction of industrially available acetylene gas, nitriles, and ketones under basic conditions has been developed. This multimolecular self-organization is triggered by the addition of acetylenic carbanions to the C≡N bond of nitrile followed by the involvement of the ketone molecule to build up the pyridine ring. The broad range of simple substrates, one-pot operation, transition-metal-free conditions, and wide variety of synthesized pyridine-tailored heterocyclic systems make the approach of high practical value alone theoretically significant.

To introduce a highly reactive acetylenic ketone function into the polysaccharide structure, arabinogalactan propargyl ethers (AGPg) with degree of substitution 1 were modified via the benzoylation of residual hydroxyl groups followed by cross-coupling of propargyl ether groups with benzoyl chloride. In the first stage, mixed propargyl ethers/benzoic esters of AG (degrees of substitution 1 and 2, respectively) were obtained in a yield of up to 95 % at room temperature in pyridine. In the second stage, the synthesized AG derivatives were involved in a palladium/copper-catalyzed cross-coupling of propargyl groups with benzoyl chloride (60-65 оC, dioxane, Et3N) to afford arabinogalactans bearing benzoate and benzoylpropargyl ether groups in 87-96 % yield (degree of substitution up to 1.0). It was found that in dilute solutions containing a 5-10-fold excess of reagents relative to propargyl groups, the reaction of AGPg with benzoyl chloride prevails over the intermolecular cross-linking, giving organosoluble products with complete conversion of the terminal acetylenes. The addition of piperidine to the activated triple bond showed that the obtained AG derivatives are promising intermediates for design of new pharmacologically oriented polysaccharides. AGPg and the original arabinogalactan were benzoylated for the first time in a two-phase aqueous-organic system (37-60 % KOH aqueous solution/dioxane) to deliver the corresponding organosoluble benzoates in 54-81 % yields and a degree of substitution 1.2-2.8.

Terminal (het)arylacetylenes react (KOBut/DMSO, 60 °C, 1 h) with N-allyl ketimines to afford 2-(het)aryl-4-(het)arylmetyl-5-ethylpyrroles in up to 71% yield as a result of the interaction of acetylenic and azadienic carbanions with C=N and C≡C bonds. This new reaction opens a one-pot access to synthetically and pharmaceutically prospective compounds.

In this work, the superbase-mediated self-organization of tetrasubstituted pyrroles from three molecules of acetylenes and one molecule of nitriles was theoretically investigated. On the example of interaction of phenylacetylene with benzonitrile in the KOBut/DMSO medium, three possible pathways of the assembly of 2-benzyl-3,5-diphenyl-4-phenylethynyl-1H-pyrrole have been studied using a combined B2PLYP-D3/6-311+G**//B3LYP-D3/6-31+G* quantum chemical approach. The calculated activation barriers correspond to mild reaction conditions (room temperature for 15 min). A preference of one of three pathways was shown and verified by kinetic modeling. The rate-determining reaction stage is the final cyclization, leading to the pyrrole core.

Herein, we disclose that two molecules of (het)arylacetylenes and two molecules of aliphatic nitriles readily undergo organization in the KOBut/DMSO system at 40 °C, forming dihydropyridines bearing imine, acetylenic, (het)aromatic and aliphatic substituents in up to 77% yield. This unprecedented reaction highlights the generality of the recently discovered self-organization of complex molecules where several acetylene units combine with simple nucleophiles, a phenomenon steered by acetylenic carbanions.

Stable pyrrole-tailored selones, 1,2,5-trisubstituted-1,2-dihydro-3H-pyrrole-3-selones, have been synthesized in up to 75% yield from aminoacetylenic ketones and elemental selenium (KOH/EtOH, room temperature, 10-11 h). The work is mainly focused on the one-pot synthesis of these compounds (50-75% yields). This synthesis has been achieved via the reactions of propargyl amines with acyl chlorides in the presence of a Pd/Cu catalyst (toluene, 40-45 °C, 2-3 h) followed by the addition of a pre-heated mixture of Se/KOH (SnCl2)/EtOH at room temperature. Our quantum-chemical calculations predict an exceptionally large ground-state dipole moment of about 7.6 Debye and an anomalously low vertical ionization energy of about 6.5 eV for the molecules under study. According to our calculations, these remarkable properties are due to the fact that the CSe bond is incorporated into the common π-system of the 3H-pyrrole ring, allowing charge transfer from N to Se. The latter effect also contributes to the exceptional stability of the reported selones.

Base-catalyzed cycloaddition of 2-acylethynylpyrroles with carbon disulfide (NaOH, DMSO, room temperature) proceeds stereoselectively to provide spirobi[pyrrolo[1,2-c]thiazoles] and pyrrolo[1,2-c]thiazole-3-thiones, both integrated with Z-α,β-ethylenic ketones in 40-81 and 35-86% yields, respectively. The switching between spirobi[pyrrolo[1,2-c]thiazoles] and pyrrolo[1,2-c]thiazole-3-thiones is controlled by the reactant ratio or the substituents in the pyrrole ring. Thus, unique pyrrolothiazole/Z-α,β-ethylenic ketone hybrids as prospective for medicinal chemistry, materials science, and organic synthesis are becoming readily accessible.

The review covers the advances reached during the last five years in transition metal free functionalization and modification of nitrogen heterocycles with electrophilic acetylenes. The reactions are triggered and further driven by the initially formed 1,3(4)-dipole complexes (zwitterions), adducts of the nucleophilic attack of nitrogen heterocycles at the triple electrophilic carbon-carbon bond of the acetylenes. The carbanionic sites of these zwitterions are usually captured by electrophiles such as second molecule of the acetylenes or other electrophilic C--C and C--O unsaturated compounds, as well as various CH-, OH-, NH-, PH-acids thereby raising molecular complexity (in the course of diverse cascade transformations) to a new higher level. The rich energy potential of the activated carbon-carbon triple bond warrants mild reaction conditions and allows the functionalization to be performed without transition metal catalysts.

3-(Pyrrol-2-yl)propynoates react with diethyl aminomalonate hydrochloride (excess Cs2CO3, reflux in MeCN, 6 h) to chemoselectively afford 8-amino-4-oxo-5,6-dihydroindolizine-7-carboxylates in good yields (62-85

The reactions of acylpropargylic alcohols with 1-pyrrolines (60 degrees C, 2-3 h) afford the acylethenyltetrahydropyrrolo[2,1-b]oxazoles and furan-3(2H)-ylideneaminoalkanones in 55-76 % and in trace to 12 % yields, respectively. Quantum-chemical calculations (B2PLYP-D3) show that formation of pyrrolo[2,1-b]oxazoles is kinetically more preferable than that of furan-3(2H)-imines, the latter being formed through 1,3(4)-dipole and 2hydroxypyrrolidine intermediates.

Possible mechanisms of cyclodimerization of benzoylethynyl pyrrole to give 2,2 '-(dipyrrolo[1,2-a:1 ',2 '-d]pyrazine-5,10-diylidene)bis(1-phenylethanone) have been investigated by using a DFT B2PLYP-D3/6-311+G**//B3LYP-D3/6-31+G*+PCM/MeCN approach. This study shows that the cyclodimerization induced by 1-methylimidazole, and that observed in the presence of strong bases (NaOH or KOH) occur by different mechanisms. The reaction pathway involving 1-methylimidazole, which starts with the formation of a zwitterionic adduct, was compared with the cyclization pathway as expected by analogy with the acylethynyl pyrrole reaction with 1-pyrroline. The C & horbar;N bond formed by the attack of the acetylene triple bond with the 1-methylimidazole molecule is maintained throughout the reaction, and the elimination of the imidazole molecule is eliminated only in the final step after pyrazine cycle formation. The formation pathways for the Z,Z-, Z,E-, and E,E-isomers of the product were analyzed. An explanation for the low yield of the final product in the presence of strong bases is proposed and the possible pathways for oligomerization of the initial benzoylethynyl pyrrole are considered.

Accessible 2-acylethynyl-4,5,6,7-tetrahydroindoles underwent stereoselective base-catalyzed (NaOH/DMSO, room temperature) [3+2]-cyclization with carbon disulfide to deliver 5,6,7,8-tetrahydro-1H,3H-thiazolo[3,4-a]indole-3-thiones incorporating Z-alpha,beta-ethylenic ketones in yields of up to 76%. The synthesized compounds were quantitatively aromatized to the indole derivatives under the action of the recyclable oxidant DDQ. The 5,6,7,8-tetrahydro- and thiazolo[3,4-a]indole-3-thiones can cyclize with another molecule of 2-acylethynylpyrroles under the above conditions to afford the corresponding 1H,1 ' H-spiro[pyrrolo[1,2-c]thiazole-3,3 '-thiazolo[3,4-a]indoles] in 54-86% yields.

It was shown for the first time that diaryl(hetaryl)ketones are capable of directly phosphorylating with red phosphorus in the superbase suspension KOH/DMSO(H2O) at 85 °C for 1.5 h to afford potassium bis(diaryl(hetaryl)methyl)phosphates that were earlier inaccessible in a yield of up to 45%. The ESR data demonstrate that unlike previously published phosphorylation with elemental phosphorus, this new phosphorylation reaction proceeds via a single electron transfer from polyphospide anions to diaryl(hetaryl)ketones. This is the first example of the C-O-P bond generation during the phosphorylation with elemental phosphorus in strongly basic media, which usually provides C-P bond formation.

Acetylene gas reacts with (het)aromatic nitriles in the KOH/ DMSO/MeOH superbase composition at 90 degrees C for 10 min to afford 2-(het)arylpyridines in up to 36% yield. The process can be rationalized as the self-organization of two molecules of acetylene and one molecule of nitrile.

Herein, we describe a synthesis and interaction with quantum dots of novel pyridyl-BODIPY.

A previously unknown class of fluorophores was discovered, which represents 14-membered bridgehead heterocycles, pyrrolyl-diazabicyclo[8.3.1]tetradecadienones, herein referred to as PY-14-ONEs. The new fluorophores are characterized by giant Stokes shifts of similar to 8000-10,250 cm-1 and virtually zero overlap of the absorption and emission bands. They exhibit fluorescence maxima in the blue-green region (454 <= lambda em <= 513 nm, MeCN), which shift to the red side when converted to their water-soluble salts by alkylation with MeI (478 <= lambda em <= 516 nm, water). PY-14-ONEs were obtained by an original synthesis from DBU, 1,8-diazabicyclo[5.4.0]undec-7-ene, which reacts with acylethynylpyrroles without catalysts under mild conditions to afford PY-14-ONEs in a 34-58% yield. The reaction represents a ring expansion of DBU. Since acylethynylpyrroles are readily available, the discovered reaction opens promising possibilities for the development of new fluorophores. The results of our time-dependent DFT calculations indicate that the pyrrole ring in PY-14-ONEs plays an important role in the formation of the Stokes shifts, which can be further enhanced by attaching appropriate substituents to it, capable of creating in S1 an extended conjugated system and causing a substantial alternation of the molecular structure via its planarization.